Hitachi TrueCopy for IBM z/OS User and Reference Guide (T5211-96001, June 2007)

7-2 TrueCopy for z/OS Usage Scenarios
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
Using TrueCopy for z/OS for Disaster Recovery
Preparing for Disaster Recovery
The type of disaster and the status of the TrueCopy for z/OS pairs will
determine the best approach for disaster recovery. For example, if all TCz
pairs are in the duplex state when a total system failure occurs at a single
point in time, the R-VOLs are current and recovery is straightforward.
Unfortunately, some disasters are not so “orderly” and involve intermittent or
gradual failures occurring over a longer period of time. The user should
anticipate and plan for all types of failures and disasters. For additional
information on planning for disaster recovery, please refer to Planning for IBM
Remote Copy, IBM document SG24-2595.
The major steps in preparing for disaster recovery are:
1. Identify the volumes and volume groups which contain important files and
data for disaster recovery, for example, DB2 log files, master catalog, key
user catalogs, and system control data sets. In addition to supporting TCz
remote copy operations as well as PPRC commands, the USP V provides
battery-backed nonvolatile duplexed cache, full hardware redundancy,
dynamic sparing, and an advanced RAID-5 implementation to ensure full data
integrity in the event of a sudden power outage or other failure.
2. Install the TrueCopy for z/OS hardware and software, and establish TCz
operations for the volumes and groups identified in step (1). Make sure to
select the proper CUs to access the desired volumes. Use the appropriate
combination of TCz options for disaster recovery:
– RCU options: Incident of RCU, FREEZE Option, Service SIM of
Remote Copy, and PPRC Support by host.
– TCzA Offloading Timer async option, TCzA Time Out (copy pending)
group option. The Time Out (copy pending) group option can be used
to limit the time duration during which updates may be lost.
– TCzA Error Level pair option, and M-VOL Fence Level pair option for
TCz Synchronous pairs.